My buddy told me if I wanna know what motor is in my car look on the back of the block on the drivers side, so I did and the numbers come up "GM 5.0L6" anyone tell me more about it?

 

5.0 Liter = a 305. Not sure about the 6 being right after, except for it meaning a casting year of 1986 (to go in an early 87 production car). No other date casting numbers near that to indicate the month & day? The suffix code on the front of the block can give more details about the engine. Camaro Decoding help on Chevy-Camaro.com